1. Field of the Invention
The invention relates to a process for closing a tap hole in the bottom of a vessel filled with a metal melt, especially a vessel for a steel melt, with a tubular closing element that is vertically movable toward and away from the entrance of the tap hole, and with a cut-off device below the vessel bottom. The invention also relates to a device for implementing a process for closing the tap hole.
2. Description of the Prior Art
The pool method for tapping a metallurgical vessel, especially a vessel for steel, uses closing systems that allow a residue of metal melt and slag to be retained in the vessel. As a rule, such vessels are designed to be tiltable, so that the closing system is not exposed to wear from the molten metal or slag.
For example, reference DE 34 37 810 discloses a closing device for a tap hole in the bottom of a metallurgical vessel, wherein a cut-off device is provided outside of and below the metallurgical vessel wherein the lower cut-off device can be moved against the tap hole from the outside. In the vessel interior, a tube is lowered from a release position into the closing position. The mouth of the tube rests against the edge of the tap hole. When the tube is in the lowered, closing position, pourable filling material is passed through the tube into the tap hole.
It is further proposed in DE 34 37 810 that the tube be closed at the foot end and that a gas be introduced into the interior to prevent the melt from entering the tube through the lower tube mouth.
In addition to experiencing high wear, the above closing device has the disadvantage of low imperviousness. In rough steel mill operation, erosion occurs at the entrance of the tap hole. Furthermore, the aggressive slag and the high melt temperatures destroy the lower edge of the closing device irregularly.